Up to 300,000 West Virginia residents spent a second night unable to bathe, shower or drink tap water on Saturday after a chemical spill into the Elk River near the state capital of Charleston.

As much as 18,927 liters of industrial chemical 4-methylcyclohexane methanol, or Crude MCHM, leaked into the river on Thursday, Governor Earl Ray Tomblin told CNN.

He declared a state of emergency for nine counties on Friday, and President Barack Obama issued an emergency declaration. The spill forced schools and businesses to close in Charleston, West Virginia's largest city.

Tomblin said that hourly tests on the affected water supply show "the chemical level is declining".

"But we're just not sure exactly how long it's going to take before it's acceptable to lift the do-not-drink ban," he said.

Jeff McIntyre, president of West Virginia American Water Co, which runs the state's largest water treatment plant, also said he could not say when the water would be safe to use.

"We don't know that the water's not safe, but I can't say it is safe," he told a news conference.

Water carrying this chemical has an odor like licorice or anise, McIntyre said, and though not highly lethal, the level that could be considered safe has yet to be quantified.

By Friday evening, 737 people had called the West Virginia Poison Center to report concerns or symptoms related to the spill, water company spokeswoman Elizabeth Scharman said.

Symptoms included nausea, vomiting, dizziness, diarrhea, rashes and reddened skin "varying from very mild to much more bothersome", Scharman said.

The center knew of 70 people who had been seen by an emergency room doctor, though only a handful had been admitted to hospitals, she said.

The spill came from a tank belonging to Freedom Industries - a Charleston company that produces specialty chemicals for the mining, steel and cement industries - upriver from a plant run by West Virginia American Water.

STRANGE ODOUR

West Virginia Department of Environmental Protection had received a report of a strange odour on Thursday morning and visited the site, where they found a leaking tank, a spokeswoman for Governor Tomblin said.

"The old tank has been emptied and taken away and as of right now the company is closed down," Tomblin said.

Tomblin said that when government officials arrived at the scene, "They had had to convince them they needed to get in to take care of this problem."

According to a letter from the Department of Environmental Protection to Freedom Industries, officials had "discovered that no spill containment measures had been initiated and that an accumulating MCHM leak pool was seeping thru a dike wall adjacent to the Elk River and a downriver oil sheen was observed."

Freedom Industries President Gary Southern said the company was still determining how much had leaked and that the company has been working with local and federal authorities, and apologized at a media conference in Charleston.

"Our friends and our neighbors, this incident is extremely unfortunate, unanticipated and we are very, very sorry for the disruption to everybody's daily life that this incident has caused," Southern said.

Emergency workers and American Water distributed water to centers around the affected area. Residents formed long lines at stores and quickly depleted inventories of bottled water.

"It's just ridiculous," said Jaime Cook of Charleston, who was buying one of the last jugs of water at a Walmart store. "There's nowhere to buy water and everywhere seems to be sold out. This isn't going to last two days."

Tina May, a Charleston resident, even considered heading out of town for the weekend. "I'm not sure how long I can last without a shower. This is unbearable," she said.

North Carolina Governor Pat McCrory on Friday waived size and weight restrictions for trucks to expedite delivery of water, equipment and supplies.